-1/2 a^{v0}_{c1} b^{c0}_{c2} c^{c1,c2}_{a0,a1} a+(a0) a+(a1) a-(v0) a-(c0)
+1/2 a^{v0}_{c1} b^{c1}_{c2} c^{c0,c2}_{a0,a1} a+(a0) a+(a1) a-(v0) a-(c0)